This invention relates to an air-conditioning system for vehicles, especially utility vehicles, having a roof opening in the area of the driver's cab for ventilation purposes.
German Offenlegungsschrift No. 33 18 708 of the assignee of the present application describes an air-conditioning unit that is to be mounted on the roof of utility vehicles, completely over the roof of the vehicle, in a compact construction, with a favorable ratio of cooling capacity to volume and weight. This air-conditioning unit comprises a condenser part having a condenser and a condenser blower and an evaporator part that is separated transversely from the condenser part, said evaporator part having an upright evaporator and a blower assigned to said evaporator. Via an opening in the roof sheeting and in the bottom side of the air-conditioning unit, circulating air is sucked from the interior of the cab and, after it has passed through the evaporator, by means of the blower, via its delivery side, is returned into the interior of the cab as cooled air. The blower assigned to the evaporator has a horizontal axis and the blower is preferably a double radial fan.
An air-conditioning unit that is to be mounted on the roof in this manner has a relatively high dead weight which leads to difficulties especially in the case of tilting cabs. The overall height of the unit above the roof sheeting of the vehicle is also relatively large because the dimensions, especially of the condenser and the evaporator, cannot be reduced if the necessary capacity of the air conditioner unit is to be achieved. When the vehicle has a spoiler that is mounted on the roof, the operation of this type of air-conditioning unit also presents problems since, as a result of the dynamic pressure support, a sufficient aeration of the condenser becomes almost impossible. When a roof opening is also provided in the cab area of the vehicle for ventilation purposes (such as the type that may be opened and closed by means of a hatch that is movable via a hinge mechanism; see, e.g., U.S. Pat. No. 4,415,197), this ventilating device must be removed when an air-conditioning unit is installed on top of the roof so that fresh air can no longer be supplied via the roof opening.
On the basis of German Offenlegungsschrift No. 21 05 296 and corresponding U.S. Pat. No. 3,670,808, an air-conditioning unit is known that is also intended for roof mounting, where a condenser and an evaporator are arranged behind one another (relative to a forward driving direction) in compartments that are separated from one another by a transversely extending wall. This results in an overall length of the air-conditioning unit that is unsuitable for the longitudinal dimensions of truck cabs. Even in the case of an inclined arrangement of the condenser, which is known on the basis of German Offenlegungsschrift No. 27 57 415, and corresponding U.S. Pat. No. 4,134,275, the overall length of the air-conditioning unit is too long for cabs of utility vehicles.
The invention aims, while overcoming the above-mentioned difficulties, to provide an air-conditioning system for vehicles, especially utility vehicles of the initially mentioned type, that is light in weight, that can be mounted as an add-on unit retrofit to vehicles, even those having a roof mounted spoiler, that works reliably, and that can be manufactured cost-effectively. In addition, it is also an object to maintain the ability to conventionally ventilate the cab through the roof opening. The invention also seeks a design that enables ventilation, air-conditioning with different capacity levels and a circulating/fresh-air supply of 0 to 100% to be made possible in different operational modes.
In accordance with preferred embodiments of the air-conditioning unit according to the invention, a tiltable hatch of an existing roof ventilation opening is removed and replaced by a receiving part that may possibly be moved by means of the existing hinge mechanisms provided for opening and closing of the roof opening hatch. By means of this mobility of the receiving part, fresh air can be supplied directly via the roof opening. This receiving part carries a blower, at the delivery side of which an air diffuser is arranged via which, in the condition of the receiving part that closes the roof opening, air can be directed into the interior to the cab as circulating air and drawn out of the interior of the cab via a circulating-air intake device that is closed off with respect to the delivery side of the blower. This permits a ventilation of the interior of the cab even when the roof opening is closed so that, even in the case of unfavorable weather conditions, such as rain, show, etc., sufficient air is supplied to the driver's cab.
The receiving part can be mounted easily because any existing hinge mechanism for the hatch of the roof ventilation opening can be used in an unchanged condition for the receiving part. Since, according to the invention, the blower is arranged approximately in the center area of the receiving part with a horizontally aligned axis, the overall height of the air-conditioning system above the vehicle roof is also relatively low. Since, in addition, the already existing roof ventilation opening in the driver's cab area can be utilized for an air-conditioning system, all installation work for the cutting of an opening into the roof sheeting of a vehicle is eliminated. The receiving part, as such, is easy to manufacture and has a relatively low dead weight even when the blower and air diffuser are provided. As a result of this low overall height of the air-conditioning system, no difficulties are encountered when installing the unit into vehicles having a spoiler that is mounted on the roof, because aeration of a condenser that is supported by dynamic pressure is not required.
In order to further reduce the height of the superstructure above the roof, of the air-conditioning system according to the invention, the receiving part has a lower center area in which the blower and the air diffuser are provided. In order to design the receiving part to fit all common sizes of roof openings, this lower center area of the receiving part has smaller dimensions than the smallest customary roof opening. In the case of such a further feature of the air-conditioning unit, the blower is partially and the air diffuser and the circulating-air intake device are completely lowered through the roof opening, so as to protrude into the interior of the cab.
The receiving part of the air-conditioning system, advantageously, is developed somewhat in keel-hulled boat shape with sides that extend upwardly beyond the blower and have upper edges that form a flat surface which receives a closure part, whereby its central area is recessed and has a trapezoidal cross-section.
In order to, irrespective of the position of the receiving part, permit a supply of fresh air and possibly also a mixing of fresh air with air-conditioned air of the air-conditioning system, a fresh-air inlet device is provided at the side of the receiving part pointing in the forward driving direction, the fresh-air supply preferably being controllable by means of a flap.
In order to ensure an even diffusion of air in the interior of the driver's cab, an air diffuser is provided that includes an air diffusion duct with several air outlet nozzles whose positions are preferably adjustable. In order to obtain a construction that is as compact as possible, a preferably vertical separating wall is provided for separating the delivery side of the blower from the circulating-air intake device, said said separating wall, at the same time, forming a limiting wall of the air diffusion duct.
In accordance with another aspect of the invention, the lower center area of the receiving part has a trapezoidal cross-section, the shorter of the parallel sides of which faces the interior of the cab. The result is that the portion of the receiving part that protrudes into the interior of the cabin is dimensioned to be as narrow as possible and, therefore, the height of the interior space is shortened only slightly and is shortened, mainly, at a point where the driver is not affected by the presence of the receiving part, particularly with respect to headroom.
According to a first of alternative embodiments of the air-conditioning system according to the invention, the top side of the receiving part is closed by means of a closure part in the form of a covering cap which is, preferably, detachably connected with the receiving part in order to provide easy and rapid access to the aggregates in the receiving part.
According to another embodiment the receiving part forms a bottom part of a housing on which an inverted trough-shaped top part is mounted to form a receiving space of sufficient size for at least one evaporator. In this way, an evaporator can, without difficulties, be mounted above the roof of the vehicle, in a manner saving space and retaining a compact overall height. As part of the air-conditioning system, the evaporator, via coolant pipes, is connected with the aggregates of the air-conditioning system, such as a condenser part and similar parts.
In the case of this alternative embodiment of the invention, the air-conditioning system not only permits the conventional direct supplying of fresh air to the interior of the driver's cab through the roof opening by movement of the receiving part, as a whole, via the existing hinge mechanism, but also enables a supplying of air-conditioned air by means of the evaporator in the upper part of the housing. Also possible is the supplying of fresh air via the fresh-air inlet device of the air-conditioning system according to the invention, so that fresh air can be mixed with the cooled circulating air. As a result, a large number of methods of operation of the air-conditioning system according to the invention is made possible with an arrangement having very small dimensions and without concern for whether a spoiler might possibly be mounted on the roof.
Various arrangements of evaporators are possible with the air-conditioning system according to the invention. The arrangement of the evaporator can take place in such a way that, according to the desired capacity requirement of the system, evaporators of different sizes and designs can be installed without a significant change of the air-conditioning system with respect to the structure. Thus the capacity can be adapted, according to the area of usage and size of the cab, to the user's requirements.
Advantageously, the bottom part of the housing and the closure part of the housing are detachably connected with one another so that the aggregates of the system are easily accessible for maintenance and repair purposes.
Additionally, a water drip for the carrying-off of condensation water produced at the evaporators is provided in the bottom part of the housing above the roof sheeting, as well as connections for the coolant pipes by means of which a connection is established, especially to the condenser and possibly also to a collecting dryer. The condenser with other aggregates can be mounted to the vehicle at any suitable point, such as the underfloor, in front of the radiator, at the wheel housing, at the frame, or a similar point, in such a way that, if possible, no housing is required for it. The condenser can then be mounted at a point where an optimal ventilation of said condenser is possible.
Advantageously, sealing means are provided at the bottom side of the receiving part or the bottom part of the housing which, in the position of the receiving part that closes the roof opening, interact with the roof sheeting in order to ensure a tight sealing therebetween. Conventionally profiled sealing or strips or similar means may be used for this purpose.
In the embodiment of the invention, the receiving part with the blower is designed to be such that it will fit into the smallest conventional roof opening yet, if necessary, in the case of a larger roof opening the same receiving part can be used without change. In addition, the bottom part of the housing and the top part of the housing are constructed to be such that the relationships of the weights and sizes of the evaporator, the blower and the housing permit an unchanged functioning of the roof opening with respect to the interior of the driver's cab. Since the air-conditioning system according to the invention, on the whole, is much lighter than previous air-conditioning units and systems, this air-conditioning system is also very suitable for tilting cabs. The height above the roof of the vehicle of the air-conditioning system is approximately maximally 100 to 120 mm when the air-conditioning system is equipped with an evaporator. Preferably, the cooling capacity, depending on the evaporator used, is approximately between 3,500 and 6,000 kcal/h.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, plural embodiments in accordance with the present invention.